Finally, I have been able to understand how the plugin system works, the differences between EGLFS and XCB and I have been able to compile and use both of this platforms.

With XCB, everything is now working fine.
With EGLFS, I have one last problem: the movement of the mouse is reaaalllyyy slow, being unusable inside the application (in the desktop the mouse movement is good). Mouse clicks and keyboard works fine, it is just the movement of the mouse.
I have configured Qt with support for libudev, as stated in the link you have posted.

Yes, I know that XCB has no support for OpenGL. Is because of this that I want to have the EGLFS platform fully working, now that I have my hands dirty compiling, installing and the like; so at any point in the future I can change between them with no more pain.

Hi,
Is your Raspberry now perfectly work with EGLFS ?
Did you find a solution for the pointer problem ?
I try to make my QtQuick2 application run on the Raspberry. I use the Raspberry2 to compile.
At the moment I have fullscreen and I have to read why there is no Window manager .. as well some problems with the Window elements positions (Buttons etc..)